Phase-locked loop (PLL) integrated circuits produce an oscillator frequency output which matches an input frequency signal. A typical PLL may include a phase-frequency detector, a charge pump, and a voltage-controlled oscillator.
Phase-locked loops are widely used in digital electronics, signal telemetry, and communications applications. Many applications require phase-locked loop (PLL) circuits which will work with high frequencies. PLL circuits can have a high sensitivity to manufacturing process variation. In particular, the voltage-controlled oscillators (VCO) are often sensitive to process variation. Thus, process yields of PLL circuits requiring high frequency operation may be reduced due to VCO frequency ranges which are out of specification. While test techniques can be used to combat this problem, the total test time significantly influences the cost of manufacturing. Accordingly, it is desirable to configure PLL circuits with an optimized test process flow and a minimized test time.